In the related art, for example, in order to increase power generation efficiency of a coal fired power plant, an Integrated Gasification Combined Cycle (IGCC) plant is developed and practically used. The IGCC plant is configured to include a gas turbine which is operated using combustible gas obtained by refining gas, which is obtained by gasifying coal by a gasification furnace, by gas clean-up equipment as a fuel, and a steam turbine which is operated by steam obtained by recovering exhaust heat of the gas turbine.
PTL 1 discloses a coal gasification power plant which gasifies coal using oxygen or oxygen enriched air produced by an oxygen production apparatus which fractions air into nitrogen and oxygen using a difference of boiling points of both, and generates electricity by a gas turbine.
Moreover, as disclosed in PTL 2, there is also an apparatus in which a slag melting burner is installed on a lower portion of a coal gasification furnace. In general, a temperature inside a combustor of a coal gasification furnace is maintained so as to be equal or higher than a melting temperature of ash in coal. However, the ash in the coal may not be temporarily discharged due to an operation state, variation in properties of coal, or the like. In this case, the slag is melted by the slag melting burner installed below a slag discharging port.